Bacterial spores contain at least two readily distinguishable morphological coat layers. Both layers contain identical keratin-like proteins and differ primarily in the higher content of half cystine residues in the outer coat layers. The morphogenesis will be studied by a number of procedures including in vitro reassembly employing electron microscopy and a quantitative immunological procedure for assay; isolation and characterization of presumptive coat mutations; and genetic experiments to map the coat mutants and possibly obtain the coat genetic region in a specific transducing phage for further mutagenesis and a study of regulation of synthesis of the structural genes. Other processes related to sporulation which will be studied are a further analysis of the regulation of synthesis of dipicolinic acid and the role of various proteases in sporulation.